Clutches and dampers for transmission applications are known. In one configuration, a clutch friction surface is disposed radially inward of the damper. Examples of standard clutches and dampers are illustrated in U.S. Pat. Nos. 6,099,435; 6,142,272; and 6,244,401, all of which are hereby incorporated herein by reference.
Current torque converter/clutch (TCC) and damper disc designs include spring pockets that use straight, uniform diameter compression springs and, by design, cause such springs to bend under axial and centrifugal loading, thus subjecting such springs to high applied stress. The straight springs have a constant spring diameter and constant coil spacing along the longitudinal length of the spring. The spring pockets in the TCC/damper disc generally have a “radius” for clearance above the spring so as to minimize contact of the spring and the spring pocket under most loading conditions, thereby limiting or preventing hysteresis, NVH (noise, vibration and harshness), spring material wear and particulate contamination, etc. The spring pockets also typically utilize a larger radius at the top of the damper pocket to achieve a larger effective radius and higher torque capacity gains during the operation of the TCC/damper disc. However, the high applied stresses on the spring during the operation of the TCC often cause premature failure of the spring which thus requires using advanced spring materials and significant and costly processing to improve fatigue life.
In view of the prior art, there is a need for an improved TCC, clutch and damper discs having improved life, and an improved spring system that can be used in a TCC, clutch and damper discs, which spring has improved spring fatigue life.